Meade |
LX20 |
Meade 8” LX200 Set

Massachusetts Institute of Technology
Department of Earth, Atmospheric, and Planetary Sciences
12.409 Hands-On Astronomy, Spring 2002
Handout 3 /week of 2002 February 11
Meade 8” LX200 Set-up
Contents
Telescope Kit Checklist...................................................................................................1
A. Items external to the telescope case.........................................................................1
B. Items inside the telescope case ................................................................................2
C. Items inside the accessory case...............................................................................2
General Usage Hints........................................................................................................3
Alignment .......................................................................................................................4
Table 1: Some Bright Stars Available For Alignment..............................................6
Packing Up......................................................................................................................6
There will be a second handout covering more advanced use of the telescope and the
extra equipment (and cases!) we’ll use. For now, this will cover the topics needed for
basic visual observing with the LX200.
Telescope Kit Checklist
Use the following checklists to
1. Alert the instructor or TA about missing pieces before beginning a night’s
observing and
2. Ensure that the kit is complete for use by your classmates next time.
A. Items external to the telescope case
1.
2.
3.
4.
5.
Tripod with C Clip, threaded rod and tension knob, and spreader bar
A Sky Atlas 2000.0, laminated edition, and Atlas Supplement notebook
120VAC power outlet strip
Counterweights
Flashlights (one red and one white)
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B. Items inside the telescope case
Meade 8” LX200 Telescope with 8” dust cover and cap for rear cell
1. Power adapter and cord
2. Handheld electronic control keypad
3. 2 coiled cords (one for keypad w/ 4 pin phone jack connectors and one for the
declination motor w/ DB-9 connectors that are slightly wider)
C. Items inside the accessory case
1.
2.
3.
4.
Finderscope
Visual back (allows connection of an eyepiece or diagonal)
Diagonal prism
7 Meade series 4000 Super Plössel eyepieces each in their own plastic case
6.4 mm (313¥ magnification, 0.17° field of view when used on f/10 Meade 8”)
9.7 mm (206¥ , 0.25°)
12.4 mm (161¥ , 0.32°)
15 mm (133¥ , 0.39°)
20 mm (100¥ , 0.52°)
26 mm (77¥ , 0.68°)
32 mm (63¥ , 0.83°)
40 mm (50¥ , 0.88°)
5. 2¥ Barlow lens
6. Eyepiece filters (Moon filter and set of color filters)
7. Light Pollution Reduction Filter
Generalized Setup Procedure
1. Attach telescope base to tripod. There’s only one screw, and it can be a bit tricky to
set it in correctly. When the telescope is screwed to the tripod correctly, there should
be no space between the base and tripod and the telescope base should not rotate.
2. Attach finderscope to main telescope (see below)
3. Level telescope (use bubble as guide, hopefully it shouldn’t be too far off).
4. Attach cables:
Dec motor to main base
Paddle to base
Plug to converter
Converter to base
5. Power up!
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FOR EMERGENCY STOP: TURN OFF POWER ON BASE
OR PULL POWER PLUG FROM BASE!
When will you need to do this? Hopefully, never. When we attach CCD cameras to the
telescopes later in IAP, however, there are situations where you realize in the middle of a
long slew that there isn’t clearance for the CCD camera to fit where it needs to. While
this is not the most elegant solution, it will work. Realize, however, that this will
necessitate realigning the telescope (see below). But that’s better than wrecking a new
telescope and CCD (hint, hint)…
General Usage Hints
1. When selecting a spot for your tripod think about how any potential obstructions
near your observing area (buildings, trees, etc…) will screen areas of the sky
2. Tripod adjustments: The tripod should be stable once you’ve secured the spreader
bar using the threaded rod with the tension knob. The length of the legs can be
adjusted using the lock knobs (bolts with star shaped handles) at the ends of the legs.
These are also used to level the telescope.
3. DO NOT EVER force the motion of the telescope; unlock the clamp first or use the
electronic keypad controls.
4. Finderscope:
The finderscope is located in the accessory case. You will need to mount it on the
telescope by sliding its bracket into the base and tightening the thumbscrews.
The view is inverted and has a field size of 5.2°.
Check the finderscope alignment before you begin observing by centering a bright
object at least 1/4 mile distant in a low-power (low magnification) eyepiece and
then see how far off this object is from the center of the crosshairs in the finder. It
will most likely need adjustment, if you want it to be centered. Ask the instructor
or a TA to show you how to use the three thumbscrews on the finder’s mount to
align it. Or remember where the position of an object that is centered in the
eyepiece is located relative to the finder crosshairs. If you choose this second
option, make sure you make a note of it in your notebook in case you forget.
5. Focusing:
The focusing mechanism is designed to allow for very fine adjustment of focus.
It takes up to 45 turns of the knob to go from focusing at close distances(which
you should not need to do in this class) to infinity.
Turning the knob counter clockwise focuses towards infinity.
It may be best to choose a partner with similar vision correction (i.e. those with
coke bottle glasses should stick together to avoid many focusing adjustments).
It is often difficult to focus on dim objects so if you are having trouble, it can be
helpful to focus on a bright object and bring the telescope back to aim at your
original object.
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6. Never wipe any optics especially the corrector plate; the anti-reflection coating is
very thing and will scratch easily. If your corrector plate becomes covered with dew,
alert your instructor or TA and we’ll use a heat gun to evaporate it off.
Alignment
The purpose of the following procedure is to allow the telescope drive motor to properly
track objects in the sky as the Earth rotates beneath them causing their apparent motion
across the sky. The LX200 telescopes are mounted in an altitude/azimuth (called alt-az
for short) format meaning that the telescope moves along vertical and horizontal axes. In
order for the LX200 to be able to track objects in the night sky properly, it must be able
to convert between altitude/azimuth coordinates along which the telescope moves and
Declination/Right Ascension coordinates along which celestial objects appear to move.
Thus, the LX200 must “know” its location, and the local date and time should all be preprogrammed (by the instructor or TA). The LX200 will store this information with the
power off so there should be no need for you to change this information until we use the
telescopes at Wallace and thus need to change the location. In addition, the LX200 must
also “know” where certain positions in the sky are located. This is accomplished by
pointing the telescope consecutively at two stars with known positions and is called
alignment. The procedure is outlined below.
1. Turn on the telescope and after the self-diagnostic start-up test is complete the display
will give you two choices (TELESCOPE and OBJECT LIBRARY).
Select Telescope (by pressing enter with the arrow pointing at Telescope).
2. Now your choices should be (SITE and ALIGN).
Press the Next key to move the arrow to Align and select it using enter.
3. The display should had two choices again (ALTAZ and POLAR).
If there is NO checkmark next to ALTAZ, press enter once and the keypad should
beep and a checkmark should appear next to ALTAZ. Now press enter again to
use the checked mode.
If there is a checkmark next to ALTAZ, press enter to use the checked mode.
4. Your choices now should be (1 Star or 2 Star Alignment).
Press next to move the arrow to 2 Star Alignment and then press enter to select it.
5. The display should now read (Level Base, then press ENTER)
This is good time to double check that the base of the telescope is level and adjust
the legs of the tripod if necessary.
When you press enter you will see (Press ENTER, then pick align star)
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6. Now you will see the beginning of the list of alignment stars contained in the
LX200’s memory.
There are 33 choices in alphabetical order so it may save you time over the course
of the semester to learn where some bright stars with names beginning with A and
B are in the sky.
Before you choose a star find it in the sky and if you are not yet familiar with
bright stars and constellations it might be worth double checking that you have
the correct star with the instructor or TA.
Press the Next key to move the arrow down the list of stars until you get to the
one you want (if you go past it use the Previous key to go back up)
Select the star by pressing enter
7. The display will read (Center “the star you chose in step 6” and then press ENTER)
You may move the telescope manually: UNLOCK the Dec and RA clamps and
point the telescope towards the star. Sight along the telescope and adjust the
telescope until you can see the star in the finder, then fine tune until it is centered
in the finder and then the eyepiece.
Or you may move the telescope electronically: Make sure the speed is set to
SLEW (this button on the keypad should be lit up). Use the N, S, E, and W
buttons to move the telescope until it is aimed at the star. When you can see it in
the finder, switch the speed to FIND to center it in the finder. Then change the
speed again to CNTR and center the star in the eyepiece.
The more carefully you center the star in the eyepiece, the more precisely your
telescope will be aligned. Early in the semester when you will be looking at
bright objects and not using the telescopes internal object library to find faint
objects, it is not important to align the telescope too precisely. Just make sure that
the star is somewhere near the center of the eyepiece. Later in the semester, when
you may want to rely on the telescope to find very faint objects, a more precise
alignment will be necessary.
Once you have centered the star in the eyepiece, press enter. Try not to delay too
much between centering the star and pressing enter since at this point the
telescope is not yet tracking the stars and thus if you wait too long the star will
drift out of the center of the eyepiece.
8. Repeat steps 6 and 7 for the second star EXCEPT FROM THIS POINT ON DO
NOT UNLOCK THE RA AND DEC CLAMPS AND ATTEMPT TO MOVE
THE TELESCOPE MANUALLY. This will result in the telescope “forgetting”
where it is pointed and you will need to start the alignment process all over. Move
the telescope only by using the keypad at speeds SLEW, FIND, or CNTR in
directions N, S, E, and W.
9. After you have completed aligning the second star, the display should read
(TELESCOPE/OBJECT LIBRARY). You are ready to use the telescope for
observation now!
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Table 1: Some Bright Stars Available For Alignment
Star
Visible in the evening in
Constellation
which semester?
Aldebaran Spring
Taurus
Alkaid
Spring or early Fall
Ursa Major (Big Dipper)
Altair
Fall
Aquila
Arcturus
Early Fall or late Spring
Bootes
Betelguese Spring
Orion
Capella
Spring
Auriga
Deneb
Fall
Cygnus
Dubhe
Fall and Spring
Ursa Major (Big Dipper)
Vega
Fall
Lyra
Magnitude (smaller
numbers are brighter)
0.87
1.85
0.76
-0.05
0.45
0.08
1.25
1.81
0.03
Packing Up
Use the telescope kit checklist to make sure you still have everything you started with
(check around the ground nearby, your pockets, and nearby telescope kits if necessary)
and that you haven’t inherited extra parts from someone else’s kit. The LX200 only fits
in the case one way so please don’t force it in the wrong way. Once in the case, unlock
the RA and Dec clamps as this will avoid damaging the drive and clamp mechanisms
during transport of the cases. Remember to remove the finderscope from the telescope
by loosening the thumbscrews on the quick-release mount. Use the checklist to make
sure the accessories get back in the proper case (be it the telescope case or the accessory
case). If after you leave class, you discover that you’ve accidentally walked off with
something from class please make sure you contact you instructor by email as soon as
possible to arrange for its return. This can be avoided by using the cases as working
storage rather than your pockets!
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